The described embodiments relate to generating a current with inverse supply voltage proportionality. Many electrical circuits require reference currents, of an amount with properties that meet the requirements for the circuit. For many integrated circuits it is necessary to generate a bias current, which keeps the circuit at a certain desired operating point. A current that is independent of the supply voltage, that is to say is constant, is often generated in this case.
What is disadvantageous in the case of such circuits is that, in the case of a falling supply voltage, the generated bias currents drop, or drop sharply at the lower end of the operating range. This is firstly due to the output conductances of the corresponding circuits, which cannot be infinite, and secondly due to the limited biasing controllability of such circuits.